786 



SCIENCE. 



[N. S. Vol. XX. No. 519. 



in our universities neither by chairs nor 

 by laboratories. We have laboratories 

 for physiology, but to show how little in- 

 terest physiologists take in general biology 

 I may mention the fact that the editor 

 of a physiological annual review excludes 

 papers on the development and fertiliza- 

 tion from his report, as in his opinion, this 

 belongs to anatomy. On the other hand, 

 anatomists and zoologists must give their 

 full energy to their morphological investi- 

 gations and have, as a rule, neither the 

 time for experimental work nor very often 

 the training necessary for that kind of 

 work. Only the botanists have kept up 

 their interest in general biology, but they 

 of course pay no attention to animal biol- 

 ogy. In working out this short review of 

 the development of biology during the last 

 century I have been impressed with the 

 necessity of our making better provisions 

 for that side of biology where, in my opin- 

 ion, the chances for the great discoveries 

 seem to lie, namely, general or experi- 

 mental biology. Jacques Loeb. 



THE PROBLEMS OF EXPERIMENTAL 

 PSYCHOLOGY.'' 



The first difficulty that confronts one, as 

 one attempts to envisage the problems of 

 experimental psychology, is the difficulty 

 of definition. What is a psychological ex- 

 periment? What is the scope of experi- 

 mental psychology? Is experiment simply 

 a method of work, applicable to all or to 

 some special parts of the psychological sys- 

 tem ; or is experimental psychology a dis- 

 tinct branch of psychology, sharply marked 

 off from other and coordinate branches ? 



The program of this congress would seem 

 to have decided the issue in the latter 

 sense ; for we find sections of general psy- 

 chology, of comparative and genetic psy- 



* Address delivered at the International Con- 

 gress of Arts and Science, St. Louis, September, 

 1904. 



chology, of abnormal psychology and of 

 social psychology, arranged alongside of 

 our own section of experimental psychol- 

 ogy. If, then, I wished to take shelter 

 behind the plan of the program, I might, 

 with some show of justification, confine my- 

 self to the discussion of those problems in 

 normal, human, adult psychology which 

 still form the staple material of experi- 

 mental investigation in the laboratories, 

 and might omit all reference to the ex- 

 tensions of the experimental method to out- 

 lying fields. Such a course would, neverthe- 

 less, be unsatisfactory. The extensions of 

 the method are coming to play a larger and 

 larger part in psychological discussions 

 and in our psychological literature; and it 

 behooves us to take up a stand with regard 

 to them, positive or negative, appreciative 

 or critical. I shall try not to shirk this 

 duty. Let me say, however, at the outset 

 — and I shall have more to say upon the 

 matter presently — that, whatever else ex- 

 perimental psychology may be, there can 

 be no doubt that the subjects to which the 

 program apparently limits us are experi- 

 mental psychology. The examination, un- 

 der strictly controlled and properly varied 

 conditions, of the normal, adult, human 

 mind— this is psychological experiment in 

 its pure, primary and typical form. And 

 it is this typical experimental psychology 

 the problems of which we have, in the first 

 place, to consider. 



In approaching this question of the prob- 

 lems of experimental psychology, it seemed 

 to me that the surest Tjey to the future lay 

 in the accomplishment of the past. The 

 best way to find out what experimental 

 psychology has to do is, I thought, to make 

 certain of what it has already done. With 

 this idea in mind, I naturally had recourse 

 to our bibliographies— the American bibli 

 ography of the Psychological Review, and 

 the German of the Zeitschrift f. Psychqlo- 

 gie. The result was not encouraging. We 



